This invention relates to drum support apparatus and more particularly to supports for photosensitive drums that prevent drum run-out.
In present reproduction machines, a problem has been encountered with photoreceptor drum radial run-out of up to 0.050 inches or more. The reason for such a deviation in tolerance lies with the drums and how they are handled in manufacturing and in the field. Hitting the rim of the drum deforms the counterbore, and an out-of-tolerance condition occurs when endbells that interference fit with the drum are reassembled in the drum. This is especially true of the inner endbell in a number of reproduction machines which is concave by about 5 inches. A slight cock in its assembly throws its shaft support bearing off center considerably due to magnification of the error by the length of the concavity. Since in a number of reproduction machines a shaft that is journaled to the machine frame is cantilevered from the frame to support a photoconductive drum without an exterior support, more run-out is observed on the inboard side of the photoconductive drum than on the outboard side.
A solution to the above-mentioned problem of drum run-out is required before improved reproduction machines can be marketed incorporating magnetic brush rollers in their development process instead of cascade development because reducing the radial drum run-out minimizes the effects of the drum tolerances on the spacing between the drum and the magnetic brush rollers.
Accordingly, it is an object of the present invention to provide a drum support apparatus that reduces drum run-out.
Another object of this invention is to reduce copier maintenance in the field.
Yet another object of this invention is to reduce the load required to properly seat the hub against the drum and thereby decrease the possibility of incurring drum run-out.